One problem encountered with the handling of ingredient cartridges is the positioning of the cartridges in an extraction device and the closing of the latter around the cartridge to perform the extraction process in a clean and hygienic manner. The cartridge usually has to be positioned by the user on a cartridge support or in a housing, then the device is closed manually or automatically around the cartridge.
It is important to correctly position the cartridge so that the device closes properly around the latter and to form a good seal to ensure good conditions of extraction. Bad positioning may damage the cartridge, and thus affect the conditions of extraction.
For the sealing of the device around the cartridge to permit proper extraction by passing a pressurized liquid through the cartridge without undesired leakage, the closing of the device around the cartridge must be carried out with a high level of precision. The closing distance of the mechanical closing arrangements of such devices are usually manually adjusted during the manufacturing process of the device to achieve the required level of precision.
The loading of the capsule must also be easy, without trial and error as to the correct position of the capsule in the device. The loading must also be as rapid as possible and not require excessive manipulations.
WO 2005/004683 relates to a capsule brewing device comprising: a first part; a second part that can be moved relative to the first part; a housing for the capsule and defining, in a closed position of the movable part against the fixed part, an extraction position of the capsule along an axis in said housing; an insertion and positioning part comprising means for guiding the capsule arranged so as to insert the capsule by gravity and position said capsule in an intermediate position; a drink pouring system; and the second movable part is so arranged and constructed to move the capsule from the intermediate position into the extraction position when the device is closed.
EP 1 721 553 discloses a brewing unit for coffee machines using capsules. The unit has a front part with a beverage outlet and a rear part with a hot water inlet. The front part and the rear part are mounted in-between a pair of facing shoulder guide members. The front part is movable in-between these guide members to be urged against the rear part so as to form with the rear part a brewing chamber for accommodating a capsule to be extracted, whereby an unoccupied volume is left in front of the front member between the guide members within the machine.
EP 1 659 547 relates to a beverage machine for making infusions, in particular, espresso coffee. The machine includes an infusion chamber within a brewing unit that has a movable front part with a return spring and a beverage outlet duct that extends through the assembly's outer housing. The movable front part cooperates with a rear part that is movable within the housing and that can be pushed against the movable front part to compress the return spring whereby the outlet duct slides through the assembly's outer housing. The pod is passed through the external housing to the infusion chamber via a rigid pod feed channel and then the pod is transferred into the infusion chamber by an external bushing on the movable rear part of the brewing unit which is provided with a cam-like path for moving the rear part. This arrangement involves several problems. The pod must be moved during the closure of the brewing chamber and this can cause blocking and it also makes the retaining means of the pod more complex. Moreover, opening and closing the brewing chamber involves simultaneously a linear displacement of the movable rear part within the housing, of the movable front part within the housing and of the outlet duct through the housing which increases the risk of hyper-guiding and jamming or improper alignment of the various parts that linearly move one relative to another. The fluid system comprises a moving assembly which makes the fluid system more complex to assemble. When upon extraction brewing unit is re-opened for removing the pod, pressurized water contained within the infusion chamber may project outside the housing. Furthermore, an unoccupied volume is left within the machine between the front member and the casing when the outlet duct is in its retracted position.
U.S. Pat. No. 3,260,190 and WO 2005/072574 disclose a coffee machine having a removable drawer for positioning a coffee can therein. The drawer can be slid horizontally into the coffee machine and lifted towards a water injection arrangement. WO 2006/023309 discloses a coffee machine with a slidable drawer for the introduction of a coffee cartridge into the machine. The drawer is movable between an open and a closed position and has two cartridge half-shells that are pivotable against each other to form a brewing chamber when the drawer is in the closed position and pivotable apart when the drawer is slid out from the machine. U.S. Pat. No. 6,966,251 discloses a coffee machine having a horizontally slidable drawer for positioning a capsule therein. When slid into the machine, the drawer can be moved upwards towards a fixed capsule cage for form a brewing chamber for a capsule. EP 1 566 126 discloses a coffee machine with a vertical brewing unit for accommodating coffee pods. The brewing unit has a fixed upper part and a movable lower part for holding a pod and that can be pulled up for closing the brewing unit and let down for inserting or removing a pod.
WO 00/49926 discloses a coffee machine having an infusion chamber with an upper part movable from a first raised position to a second lowered position and a lower part made on a movable trolley arranged below the upper part.
Further brewing units are disclosed in EP 0 730 425, EP 0 862 882, EP 1 219 217, EP 1 480 540, EP 1 635 680, EP 1 669 011, EP 1 774 878, EP 1 776 026, EP 1 893 064, FR 2 424 010, U.S. Pat. No. 3,260,190, U.S. Pat. No. 4,760,774, U.S. Pat. No. 5,531,152, U.S. Pat. No. 6,904,840, U.S. Pat. No. 7,131,369, US 2005/0106288, US 2006/0102008, WO 2005/002405, WO 2005/016093, WO 2006/005756, WO 2006/066626 and WO 2007/135136.
To avoid the problem relating to precise mechanical closing of the extraction device around an ingredient cartridge, it is known to provide a hydraulic closure system in which the heated water used for extracting an ingredient in a cartridge is also used to actuate a hydraulic closure mechanism. In this case, the closing distance does not require special adjustment since the hydraulic closing force urges the cartridge supports of the extraction device together around the cartridge. An example of such a system is for instance disclosed in WO 2008/037642. Various systems have been developed along this idea, as for instance discussed in EP 1 219 217, EP 1 480 540, EP 1 776 026, EP 1 912 542, WO 2005/115206, and WO 2006/005736.
A problem with using heated water to actuate the closure mechanism lies in the risk of scale deposition from the heated water in the hydraulic mechanism.
It has been proposed in EP 1 545 278 to implement two parallel water lines connected to a single water source and both controlled by a common multi-way valve. One water circulation circuit, the extraction circuit, passes via a heater into the extraction device and the other water line, unheated, is used for the hydraulic closure of the extraction device. In a first step, the multi-way valve permits supply of pressurized water to the hydraulic closure system of the extraction device. Once the extraction device is closed, the pressure built up in the hydraulic closure system by the presence of the pressurized static, forces the circulation of water in the second line through a check valve into the extraction device via the heater. Once extraction is over, the common multi-way valve is moved into a position to connect the hydraulic closure system with a purging circuit to evacuate the pressurized water that had been statically captured in the hydraulic water circuit during extraction and to evacuate the surplus water not injected into the extraction circuit. A similar system is disclosed in EP 1 353 591.
One problem with this solution lies in the complication of the parallel water circuits for the hydraulic closure and for the hot injection and the multi-way control valve associated therewith. Another problem with this system lies in the fact that by having to purge the hydraulic water circuit upon each and every extraction cycle, the circuit must first be replenished before being operative for closing the brewing unit. However, since the liquid is non-circulating, stagnant in the hydraulic closure system during the extraction process purging is necessary to avoid contamination and hygiene-related issues in this part of the circuit.
The principle, as such, of purging the fluid circuit of a beverage preparation machine is known in the field. For example, EP 1 764 014 discloses a beverage preparation machine with a fluid circuit including a pump and inline thermoblock heaters leading to hot water, steam and beverage dispensing outlets. The fluid circuit includes a fluid evacuation valve at the inlet sides of the heaters to reduce scale deposition in the serpentines of the thermoblocks. The evacuation valve at the inlet sides of the thermoblocks cooperate with a valve downstream the thermoblock that is opened simultaneously for venting the thermoblock, i.e. replacing the fluid by air in the thermoblock. This operation is carried out once a thermoblock has not been used for a defined time period. In other words, the this operation makes sense to be carried out when the machine is idling or goes idling for an extended period of time or when shut down or when entering a standby mode.
Another problem relates to the dripping of liquid form the beverage machine's outlet after a dispensing cycle is over. This may happened when the system is maintained in a state of immediate readiness for a further extraction cycle, i.e. with the water circuit filled with water instead of being empty. This contrasts with systems that are purged each time immediately after a beverage preparation cycle is over, as disclosed in the abovementioned EP 1 545 278 with its multi-way valve for purging parallel water circuits for the extraction and for the hydraulic closure.
Indeed, especially with the preparation of coffee or tea by extracting ground coffee or tea in a brewing chamber that leads to a beverage outlet, drips tend to be formed at the beverage outlet for an extend period of time after the machine's pump has been shut off and the system is not purged to maintain immediate readiness for a further extraction cycle. Moreover, at the end of an extraction cycle, the user wonders when he or she should pick up the cup from under the beverage outlet as the dispensing still seems to continue at a slow, dripping pace after shut-off of the pump. To avoid that the machine and/or its surrounds get dirty by such drips, it can be fitted with a drip collector positioned under the beverage outlet to collect the drips upon removal of the filled cup from under the outlet. Examples of such drip collectors are for example disclosed in EP 1 867 260, EP 1 811 881 and WO 2009/074557.
These drip collectors provide a solution for the hygiene problem resulting from such drips. There is however still a need for a solution to the unclear end of a beverage dispensing cycle, so that a user does not have to wonder when to remove his of her cup from under the beverage outlet.